If 400,000 = 4^(n+1) * 25^n , then n = a) 1.5 b) 2 c)

Question

If 400,000 = 4^(n+1) * 25^n , then n = 

a) 1.5
b) 2
c) 2.5
d) 3
e) 3.5

anindyat · Answer

4^(n+1) * 25^n = 400,000
=> 4 * 4 ^ n * 25 ^ n = 4 * 10 ^ 5
=> 4 * (4 * 25) ^ n = 4 * 10 ^ 5
=> 4 * 100 ^ n = 4 * 10 ^ 5
=> 4 * 10 ^ 2n = 4 * 10 ^ 5

2n = 5
n = 2.5

Cedars · Answer

answer is D.

you just need to simplify the exponents.

4^(n+1)*(25^n) is the same as (2^2n * 2^2)(5^2n) ===> 

4*10^2n; now 10^2n is the same as 100*10^n therefore

4*100*10^n is equal to 400*10^n.

400,000 = 400*10^n 
1000 = 10^n
n = 3

Hope that helps

AK47 · Answer

hi cedar,
this step of ur'sbis not right

now 10^2n is the same as 100*10^n

because 100 * 10^n = 10^(2+n) and not 10^ 2n

ans is 2.5

londonluddite · Answer

Well done peeps the OA is 2.5

anandsebastin · Answer

Brrrr... this is what scares me... reading 400,000 as 40,000. :roll:

ivymba · Answer

made the same mistake ...... :arh

If 400,000 = 4^(n+1) * 25^n , then n = a) 1.5 b) 2 c)

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